the thermocouple arrived. let the games begin. video, caveats, etc. below.obvious revelation no. 1: the brewing temp is all over the map. at issue, then, is a flush and recover routine (to bleed the superheated water sitting in the group) that results in the most stable possible brewing temperature somewhere between 199 and 203 degrees (most espressos, and most tongues, like it somewhere in there). for me, this effort consummates and hearkens to all sorts of important touchstones of home brewing, specifically with an e61 grouphead and heat exchanger. wanna talk about why certain beans or blends do or do not brew optimally on a home machine? wanna talk flushing a heat exchanger for the proper brew temp? how about boiler pressure as a proxy for temp, or the reliability of tuning charts, or the upsides and downsides of flushing? all these are factors and tangents that have floated in my head for awhile. the precipitating factor: shots of a yirg that i knew was superior ending up all over the board — sour, bitter, uber-winey, etc. thus the videotaped, thermoprobed, highly experimental temperature control data collection.
my best flushing routine so far (using an isomac tea) is here. video’s 7MB, so dial-up users be warned.
in case you have trouble reading the titles, here’s the gist.

* i begin the flush and adjust the thermocouple, so the tip is directly in the stream of water. the water temp falls from 97 celcius (206.6).
* once the hissing stops, i then wait for the boiler needle to dip to its lowest point before cycling back up — or roughly to a count of five. stop the flush when the needle flutters at the bottom (1,1 bar or so, for me) and prepares to head back up.
* wait for the needle to fully cycle through twice, heating, then cooling, then heating, then cooling. on a tea, watch your lights and brew at the third green light.
* the target brewing range is 93 to 95 on the readout — roughly 199 to 203 degrees F. the entire shot should then pull within this range.

even as i write this, some even more studious minds are birthing still more eureka moments with such machines. one step at a time, i say. i’ll get to synesso-like shot clarity when i first nail a consistently-obscure-but-good shot nine times out of 10…